Question

Create a flowchart to represent the Push and Pop operations for a Stack based on a linked list data structure.

Create a flowchart to represent the Enqueue and Dequeue operations for a Queue based on a linked list data structure.

Write the required Java code to implement either a Stack or a Queue data structure based on a linked list. The code should include the class constructors, the necessary properties, and methods to add and remove elements from the data structure. Do not use the built-in Java Stack class or the built-in Java Queue interface or the built-in Java linked list (you should create your own code for these classes).

Answer 1

//Java program

//node class
class Node{
   private int data;
   private Node next;
  
   public Node(int d) {
       data = d;
       next=null;
   }
   public int getData() {
       return data;
   }
   public Node getNext() {
       return next;
   }
   public void setNext(Node n) {
       next = n;
   }
}
//stack class
class Stack{
   private Node top;
  
   public Stack() {
       top=null;
   }
   public void push(int d) {
       Node node = new Node(d);
       node.setNext(top);
       top = node;
   }
   public void pop() {
       if(top==null)return;
       top = top.getNext();
   }
   public int getTop() {
       return top.getData();
   }
}

//Queue class
class Queue{
   private Node front,rear;
  
   public Queue() {
       front=null;
       rear = null;
   }
   public void enqueue(int d) {
       Node node = new Node(d);
       if(rear==null) {
           rear = node;
           front = rear;
           return;
       }
       rear.setNext(node);
       rear = node;
   }
   public void dequeue() {
       if(front==null)return;
       if(front==rear) {
           front=null;
           rear=null;
           return;
       }
       front = front.getNext();
   }
   public int getFront() {
       return front.getData();
   }
}